Vessel Pose Determination Using Camera Horizon Detection
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Solution Overview
Problem
Existing maritime navigation systems face challenges in accurately determining the pose parameters of a vessel, particularly orientation, due to unreliable GPS signals and inaccurate inertial measurement units (IMUs), especially during long-lasting accelerations.
Innovation Solution
A method and system using a camera to capture images of solid objects and their interfaces with the sky or water, processing these images to determine precise pose parameters by comparing image data with reference data, allowing for calibration and verification of IMU estimates without relying on IMUs, and enabling cost-efficient and automatic precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If GPS receiver and IMU are used to determine pose parameters, then coarse position and orientation estimates can be obtained, but measurement precision deteriorates due to signal corruption and inaccurate IMU readings during accelerations
Solution Approach 1:
The patent introduces an intermediary system consisting of a camera and image processing algorithms that mediates between the unreliable GPS/IMU system and the required precise pose parameters. The camera captures images of the horizon or water surface, and through image processing, derives accurate orientation parameters independent of GPS signal quality or IMU acceleration errors.
Solution Approach 2:
The patent replaces the mechanical inertial measurement system (IMU) with an optical measurement system (camera-based horizon/water surface detection). This substitution eliminates the fundamental limitation of IMUs during accelerations, as the optical method directly measures orientation relative to the horizon or water surface without being affected by dynamic forces.
2Measurement precision
If IMU is used to determine orientation, then coarse orientation estimates are available, but measurement precision worsens during long-lasting accelerations
Solution Approach 1:
The patent replaces the acceleration-sensitive mechanical IMU system with an optical system that uses a camera to detect the horizon or water surface. This substitution removes the vulnerability to acceleration effects, as the optical measurement directly captures the true orientation relative to the reference plane regardless of dynamic forces acting on the vessel.
Solution Approach 2:
The camera-based system acts as an intermediary that provides a direct optical measurement of orientation, bypassing the flawed mechanical sensing chain of the IMU. By processing images of the horizon or water surface, the system derives accurate orientation parameters that are immune to acceleration-induced errors.
3Reliability
If traditional GPS and IMU systems are used, then pose estimation can be performed, but device complexity increases and reliability decreases
Solution Approach 1:
The patent merges the camera system with the existing GPS receiver to form an integrated pose determination system. The camera and GPS work together, with the camera providing orientation information and the GPS providing position information, creating a unified system that is more reliable than either component alone while avoiding the need for a separate, complex IMU system.
Solution Approach 2:
The camera serves multiple functions: it captures images for horizon/water surface detection to determine orientation, can also provide visual data for position verification, and enables post-processing calibration of the IMU. This multi-functionality reduces the need for dedicated specialized components, thereby reducing overall system complexity while improving reliability.
Data Source
AI summary
A method and a system for determining a precise value of at least one pose parameter of an ego vessel, on which a camera is arranged, is provided. The method includes receiving image data of an image captured by the camera, the image showing at least one solid object and at least one solid object interface between the solid object and the sky, or between the solid object and a water surface of a waterbody, on which the ego vessel sails, determining a first representation of the solid object interface, determining a coarse position of the ego vessel, determining reference data based on the coarse position of the ego vessel, determining a second representation of the solid object interface from the reference data, determining a difference between the first and second representation, and determining the precise value of the pose parameter of the ego vessel depending on the difference.